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  <div class="section" id="generic-operating-system-services">
<span id="allos"></span><h1>16. Generic Operating System Services<a class="headerlink" href="#generic-operating-system-services" title="Permalink to this headline">¶</a></h1>
<p>The modules described in this chapter provide interfaces to operating system
features that are available on (almost) all operating systems, such as files and
a clock.  The interfaces are generally modeled after the Unix or C interfaces,
but they are available on most other systems as well.  Here&#8217;s an overview:</p>
<ul>
<li class="toctree-l1"><a class="reference external" href="os.html">16.1. <tt class="docutils literal"><span class="pre">os</span></tt> &#8212; Miscellaneous operating system interfaces</a><ul>
<li class="toctree-l2"><a class="reference external" href="os.html#process-parameters">16.1.1. Process Parameters</a></li>
<li class="toctree-l2"><a class="reference external" href="os.html#file-object-creation">16.1.2. File Object Creation</a></li>
<li class="toctree-l2"><a class="reference external" href="os.html#file-descriptor-operations">16.1.3. File Descriptor Operations</a></li>
<li class="toctree-l2"><a class="reference external" href="os.html#files-and-directories">16.1.4. Files and Directories</a></li>
<li class="toctree-l2"><a class="reference external" href="os.html#process-management">16.1.5. Process Management</a></li>
<li class="toctree-l2"><a class="reference external" href="os.html#miscellaneous-system-information">16.1.6. Miscellaneous System Information</a></li>
<li class="toctree-l2"><a class="reference external" href="os.html#miscellaneous-functions">16.1.7. Miscellaneous Functions</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference external" href="io.html">16.2. <tt class="docutils literal"><span class="pre">io</span></tt> &#8212; Core tools for working with streams</a><ul>
<li class="toctree-l2"><a class="reference external" href="io.html#module-interface">16.2.1. Module Interface</a></li>
<li class="toctree-l2"><a class="reference external" href="io.html#i-o-base-classes">16.2.2. I/O Base Classes</a></li>
<li class="toctree-l2"><a class="reference external" href="io.html#raw-file-i-o">16.2.3. Raw File I/O</a></li>
<li class="toctree-l2"><a class="reference external" href="io.html#buffered-streams">16.2.4. Buffered Streams</a></li>
<li class="toctree-l2"><a class="reference external" href="io.html#text-i-o">16.2.5. Text I/O</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference external" href="time.html">16.3. <tt class="docutils literal"><span class="pre">time</span></tt> &#8212; Time access and conversions</a></li>
<li class="toctree-l1"><a class="reference external" href="optparse.html">16.4. <tt class="docutils literal"><span class="pre">optparse</span></tt> &#8212; More powerful command line option parser</a><ul>
<li class="toctree-l2"><a class="reference external" href="optparse.html#background">16.4.1. Background</a><ul>
<li class="toctree-l3"><a class="reference external" href="optparse.html#terminology">16.4.1.1. Terminology</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#what-are-options-for">16.4.1.2. What are options for?</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#what-are-positional-arguments-for">16.4.1.3. What are positional arguments for?</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference external" href="optparse.html#tutorial">16.4.2. Tutorial</a><ul>
<li class="toctree-l3"><a class="reference external" href="optparse.html#understanding-option-actions">16.4.2.1. Understanding option actions</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#the-store-action">16.4.2.2. The store action</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#handling-boolean-flag-options">16.4.2.3. Handling boolean (flag) options</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#other-actions">16.4.2.4. Other actions</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#default-values">16.4.2.5. Default values</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#generating-help">16.4.2.6. Generating help</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#printing-a-version-string">16.4.2.7. Printing a version string</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#how-optparse-handles-errors">16.4.2.8. How <tt class="docutils literal"><span class="pre">optparse</span></tt> handles errors</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#putting-it-all-together">16.4.2.9. Putting it all together</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference external" href="optparse.html#reference-guide">16.4.3. Reference Guide</a><ul>
<li class="toctree-l3"><a class="reference external" href="optparse.html#creating-the-parser">16.4.3.1. Creating the parser</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#populating-the-parser">16.4.3.2. Populating the parser</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#defining-options">16.4.3.3. Defining options</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#standard-option-actions">16.4.3.4. Standard option actions</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#option-attributes">16.4.3.5. Option attributes</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#standard-option-types">16.4.3.6. Standard option types</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#parsing-arguments">16.4.3.7. Parsing arguments</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#querying-and-manipulating-your-option-parser">16.4.3.8. Querying and manipulating your option parser</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#conflicts-between-options">16.4.3.9. Conflicts between options</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#cleanup">16.4.3.10. Cleanup</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#other-methods">16.4.3.11. Other methods</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference external" href="optparse.html#option-callbacks">16.4.4. Option Callbacks</a><ul>
<li class="toctree-l3"><a class="reference external" href="optparse.html#defining-a-callback-option">16.4.4.1. Defining a callback option</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#how-callbacks-are-called">16.4.4.2. How callbacks are called</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#raising-errors-in-a-callback">16.4.4.3. Raising errors in a callback</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#callback-example-1-trivial-callback">16.4.4.4. Callback example 1: trivial callback</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#callback-example-2-check-option-order">16.4.4.5. Callback example 2: check option order</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#callback-example-3-check-option-order-generalized">16.4.4.6. Callback example 3: check option order (generalized)</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#callback-example-4-check-arbitrary-condition">16.4.4.7. Callback example 4: check arbitrary condition</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#callback-example-5-fixed-arguments">16.4.4.8. Callback example 5: fixed arguments</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#callback-example-6-variable-arguments">16.4.4.9. Callback example 6: variable arguments</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference external" href="optparse.html#extending-optparse">16.4.5. Extending <tt class="docutils literal"><span class="pre">optparse</span></tt></a><ul>
<li class="toctree-l3"><a class="reference external" href="optparse.html#adding-new-types">16.4.5.1. Adding new types</a></li>
<li class="toctree-l3"><a class="reference external" href="optparse.html#adding-new-actions">16.4.5.2. Adding new actions</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference external" href="getopt.html">16.5. <tt class="docutils literal"><span class="pre">getopt</span></tt> &#8212; Parser for command line options</a></li>
<li class="toctree-l1"><a class="reference external" href="logging.html">16.6. <tt class="docutils literal"><span class="pre">logging</span></tt> &#8212; Logging facility for Python</a><ul>
<li class="toctree-l2"><a class="reference external" href="logging.html#logging-tutorial">16.6.1. Logging tutorial</a><ul>
<li class="toctree-l3"><a class="reference external" href="logging.html#simple-examples">16.6.1.1. Simple examples</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#loggers">16.6.1.2. Loggers</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#handlers">16.6.1.3. Handlers</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#formatters">16.6.1.4. Formatters</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#configuring-logging">16.6.1.5. Configuring Logging</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#configuring-logging-for-a-library">16.6.1.6. Configuring Logging for a Library</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference external" href="logging.html#logging-levels">16.6.2. Logging Levels</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#logger-objects">16.6.3. Logger Objects</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#basic-example">16.6.4. Basic example</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#logging-to-multiple-destinations">16.6.5. Logging to multiple destinations</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#adding-contextual-information-to-your-logging-output">16.6.6. Adding contextual information to your logging output</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#sending-and-receiving-logging-events-across-a-network">16.6.7. Sending and receiving logging events across a network</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#handler-objects">16.6.8. Handler Objects</a><ul>
<li class="toctree-l3"><a class="reference external" href="logging.html#module-logging.handlers">16.6.8.1. StreamHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#filehandler">16.6.8.2. FileHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#watchedfilehandler">16.6.8.3. WatchedFileHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#rotatingfilehandler">16.6.8.4. RotatingFileHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#timedrotatingfilehandler">16.6.8.5. TimedRotatingFileHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#sockethandler">16.6.8.6. SocketHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#datagramhandler">16.6.8.7. DatagramHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#sysloghandler">16.6.8.8. SysLogHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#nteventloghandler">16.6.8.9. NTEventLogHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#smtphandler">16.6.8.10. SMTPHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#memoryhandler">16.6.8.11. MemoryHandler</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#httphandler">16.6.8.12. HTTPHandler</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference external" href="logging.html#formatter-objects">16.6.9. Formatter Objects</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#filter-objects">16.6.10. Filter Objects</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#logrecord-objects">16.6.11. LogRecord Objects</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#loggeradapter-objects">16.6.12. LoggerAdapter Objects</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#thread-safety">16.6.13. Thread Safety</a></li>
<li class="toctree-l2"><a class="reference external" href="logging.html#configuration">16.6.14. Configuration</a><ul>
<li class="toctree-l3"><a class="reference external" href="logging.html#configuration-functions">16.6.14.1. Configuration functions</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#configuration-file-format">16.6.14.2. Configuration file format</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#configuration-server-example">16.6.14.3. Configuration server example</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference external" href="logging.html#more-examples">16.6.15. More examples</a><ul>
<li class="toctree-l3"><a class="reference external" href="logging.html#multiple-handlers-and-formatters">16.6.15.1. Multiple handlers and formatters</a></li>
<li class="toctree-l3"><a class="reference external" href="logging.html#using-logging-in-multiple-modules">16.6.15.2. Using logging in multiple modules</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference external" href="getpass.html">16.7. <tt class="docutils literal"><span class="pre">getpass</span></tt> &#8212; Portable password input</a></li>
<li class="toctree-l1"><a class="reference external" href="curses.html">16.8. <tt class="docutils literal"><span class="pre">curses</span></tt> &#8212; Terminal handling for character-cell displays</a><ul>
<li class="toctree-l2"><a class="reference external" href="curses.html#functions">16.8.1. Functions</a></li>
<li class="toctree-l2"><a class="reference external" href="curses.html#window-objects">16.8.2. Window Objects</a></li>
<li class="toctree-l2"><a class="reference external" href="curses.html#constants">16.8.3. Constants</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference external" href="curses.html#module-curses.textpad">16.9. <tt class="docutils literal"><span class="pre">curses.textpad</span></tt> &#8212; Text input widget for curses programs</a><ul>
<li class="toctree-l2"><a class="reference external" href="curses.html#textbox-objects">16.9.1. Textbox objects</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference external" href="curses.html#module-curses.wrapper">16.10. <tt class="docutils literal"><span class="pre">curses.wrapper</span></tt> &#8212; Terminal handler for curses programs</a></li>
<li class="toctree-l1"><a class="reference external" href="curses.ascii.html">16.11. <tt class="docutils literal"><span class="pre">curses.ascii</span></tt> &#8212; Utilities for ASCII characters</a></li>
<li class="toctree-l1"><a class="reference external" href="curses.panel.html">16.12. <tt class="docutils literal"><span class="pre">curses.panel</span></tt> &#8212; A panel stack extension for curses.</a><ul>
<li class="toctree-l2"><a class="reference external" href="curses.panel.html#functions">16.12.1. Functions</a></li>
<li class="toctree-l2"><a class="reference external" href="curses.panel.html#panel-objects">16.12.2. Panel Objects</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference external" href="platform.html">16.13. <tt class="docutils literal"><span class="pre">platform</span></tt> &#8212;  Access to underlying platform&#8217;s identifying data.</a><ul>
<li class="toctree-l2"><a class="reference external" href="platform.html#cross-platform">16.13.1. Cross Platform</a></li>
<li class="toctree-l2"><a class="reference external" href="platform.html#java-platform">16.13.2. Java Platform</a></li>
<li class="toctree-l2"><a class="reference external" href="platform.html#windows-platform">16.13.3. Windows Platform</a><ul>
<li class="toctree-l3"><a class="reference external" href="platform.html#win95-98-specific">16.13.3.1. Win95/98 specific</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference external" href="platform.html#mac-os-platform">16.13.4. Mac OS Platform</a></li>
<li class="toctree-l2"><a class="reference external" href="platform.html#unix-platforms">16.13.5. Unix Platforms</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference external" href="errno.html">16.14. <tt class="docutils literal"><span class="pre">errno</span></tt> &#8212; Standard errno system symbols</a></li>
<li class="toctree-l1"><a class="reference external" href="ctypes.html">16.15. <tt class="docutils literal"><span class="pre">ctypes</span></tt> &#8212; A foreign function library for Python.</a><ul>
<li class="toctree-l2"><a class="reference external" href="ctypes.html#ctypes-tutorial">16.15.1. ctypes tutorial</a><ul>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#loading-dynamic-link-libraries">16.15.1.1. Loading dynamic link libraries</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#accessing-functions-from-loaded-dlls">16.15.1.2. Accessing functions from loaded dlls</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#calling-functions">16.15.1.3. Calling functions</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#fundamental-data-types">16.15.1.4. Fundamental data types</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#calling-functions-continued">16.15.1.5. Calling functions, continued</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#calling-functions-with-your-own-custom-data-types">16.15.1.6. Calling functions with your own custom data types</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#specifying-the-required-argument-types-function-prototypes">16.15.1.7. Specifying the required argument types (function prototypes)</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#return-types">16.15.1.8. Return types</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#passing-pointers-or-passing-parameters-by-reference">16.15.1.9. Passing pointers (or: passing parameters by reference)</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#structures-and-unions">16.15.1.10. Structures and unions</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#structure-union-alignment-and-byte-order">16.15.1.11. Structure/union alignment and byte order</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#bit-fields-in-structures-and-unions">16.15.1.12. Bit fields in structures and unions</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#arrays">16.15.1.13. Arrays</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#pointers">16.15.1.14. Pointers</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#type-conversions">16.15.1.15. Type conversions</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#incomplete-types">16.15.1.16. Incomplete Types</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#callback-functions">16.15.1.17. Callback functions</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#accessing-values-exported-from-dlls">16.15.1.18. Accessing values exported from dlls</a></li>
<li class="toctree-l3"><a class="reference external" href="ctypes.html#surprises">16.15.1.19. Surprises</a></li>
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